﻿//
// (C) Copyright 2009 Irantha Suwandarathna (iranthas@hotmail.com)
// All rights reserved.
//

/* Copyright (c) 2001-2008, The HSQL Development Group
 * All rights reserved.
 *
 * Redistribution and use _in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions _in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer _in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of the HSQL Development Group nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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using System;
using System.Collections.Generic;
using System.Linq;
#if !SILVERLIGHT
using System.Data.Common;
using System.Data;
#endif
using System.Text;
using EffiProz.Core;
using EffiProz.Core.Errors;

namespace EffiProz.Core.DataTypes
{
    /**
     * Type subclass for untyped NULL values.<p>
     *
     * @author Fred Toussi (fredt@users dot sourceforge.net)
     * @version 1.9.0
     * @since 1.9.0
     */
    public sealed class NullType : SqlType
    {

        public static NullType nullType = new NullType();

        private NullType()
            : base(Types.SQL_ALL_TYPES, Types.SQL_ALL_TYPES, 0, 0)
        {

        }

        public override int displaySize()
        {
            return 4;
        }

        public override int getAdoTypeCode()
        {
#if !SILVERLIGHT
            return (int)DbType.Object;
#else
            return -1;
#endif
        }

        public override String getCSharpClassName()
        {
            return "System.Void";
        }

        public override String getNameString()
        {
            return Tokens.T_NULL;
        }

        public override String getDefinition()
        {
            return Tokens.T_NULL;
        }

        public override SqlType getAggregateType(SqlType other)
        {
            return other;
        }

        public override SqlType getCombinedType(SqlType other, int operation)
        {
            return other;
        }

        public override int compare(Session session, Object a, Object b)
        {
            throw Error.runtimeError(ErrorCode.U_S0500, "NullType");
        }

        public override Object convertToTypeLimits(SessionInterface session, Object a)
        {
            return null;
        }

        public override Object convertToType(SessionInterface session, Object a,
                                    SqlType otherType)
        {
            return null;
        }

        public override Object convertToDefaultType(SessionInterface session, Object a)
        {
            return null;
        }

        public override String convertToString(Object a)
        {
            throw Error.runtimeError(ErrorCode.U_S0500, "NullType");
        }

        public override String convertToSQLString(Object a)
        {
            throw Error.runtimeError(ErrorCode.U_S0500, "NullType");
        }

        public override bool canConvertFrom(SqlType otherType)
        {
            return true;
        }

        public static SqlType getNullType()
        {
            return nullType;
        }
    }
}
